Service manual

Refrigeration System Section 7
7-14
Part No. 80-1206-3
Safety Limit #2
Control Board with Black Microprocessor - Harvest time exceeds 3.5 minutes for 3 consecutive harvest cycles.
or
Control Board with Orange Label on Microprocessor - Harvest time exceeds 3.5 minutes for 500 consecutive
harvest cycles.
QDUALC ONLY - Harvest cycle time exceeds 7 minutes for 3 consecutive harvest cycles.
SAFETY LIMIT NOTES
• Because there are many possible external problems,
do not limit your diagnosis to only the items listed in
this chart.
• A continuous run of 100 harvests automatically
erases the safety limit code.
• The control board will store and indicate only one
safety limit – the last one exceeded.
• If the toggle switch is moved to the OFF position and
then back to the ICE position prior to reaching the
100-harvest point, the last safety limit exceeded will
be indicated.
• If the harvest light did not flash prior to the ice
machine restarting, then the ice machine did not stop
because it exceeded a safety limit.
SAFETY LIMIT STAND-BY MODE
(QDUAL ONLY)
The first time a safety limit shut down occurs, the ice
machine turns off for 60 minutes (Stand By Mode). The
ice machine will then automatically restart to see if the
problem re-occurs. During the Stand By Mode the
harvest light will be flashing continuously and a safety
limit indication can be viewed. If the same safety limit is
reached a second time (the problem has re-occurred 3
more consecutive time) the ice machine will initiate a
safety limit shut down and remain off until it is manually
restarted. During a safety limit shut down the harvest
light will be flashing continuously.
Possible Cause Check/Correct
Improper installation
See “Installation/Visual Inspection Checklist”
Water system Water area (evaporator) dirty
Dirty/defective water dump valve
Vent tube not installed on water outlet drain
Water freezing behind evaporator
Plastic extrusions and gaskets not securely mounted to the
evaporator
Dirty/defective float valve (Q1400C Only)
Electrical system Ice thickness probe out of adjustment (premature harvest)
Ice thickness probe dirty
Bin switch defective
Refrigeration system Non-Manitowoc components
Improper (low or overcharge) refrigerant charge
Defective head pressure control valve
Defective cool vapor valve
Defective fan cycling control (CVD0675/CVD1476 do not have
a fan cycle control)
CVD1476 Only - Water inlet valve is incorrectly adjusted or will
not close during harvest cycle.